Linus describes how he prefers new features to be introduced to Linux:

In other words, every new crazy feature should be hidden in a nice solid "Trojan Horse" gift: something that looks _obviously_ good at first sight.

The fact that it may contain the germs for future features should be hidden so well that not only is it not used as an argument ("Hey, look at all those soldiers in that horse, imagine what you could do with them"), it should also not be obvious from the source code ("Look at all those hooks I sprinkled around, which aren't actually used by anything, but just imagine what you could do with them").
Linus